Forecasting transboundary river water elevations from space

1 Department of Civil and Environmental Engineering, University of Washington 2 Department of Civil and Environmental Engineering, Tennessee Technological University

Abstract : Over 90% of Bangladesh-s surface water is generated upstream of its border, yet no real-time information is shared by India the upstream country with respect to two major transboundary rivers, the Ganges and Brahmaputra. This constraint limits operational forecasts of river states inside Bangladesh to lead times of no more than three days. Topex-Poseidon satellite altimetry measurements of water levels in India, combined with in-situ measurements inside Bangladesh allow extension of this lead time. We show that for both rivers, it is practically feasible to forecast water elevation anomalies during the critical monsoon season June to September near the Bangladesh border with an RMSE of about 0.40 m for lead times up to 5-days. Longer 10-day forecasts have higher errors RMSE between 0.60 m and 0.80 m but still provide useful information for operational applications. These results demonstrate the tremendous potential of satellite altimetry for transboundary river management.